Electric timepiece



R. JEANMONOD ELECTRIC TIMEPIECE Sept. 9, 1969 Filed Sept. 26, 1967 llii2 I :nu

ffy 4 Il Il llll 3 I' llll 3' INVENTOR ROLAN D v CJEANMONOD zum!ATTORNEY United States Patent O 3,465,510 ELECTRIC TIMEPIECE RolandJeanmonod, Peseux, Switzerland, assignor to Ebauches S.A., Canton ofNeuchatel, Switzerland, a

Filed Sept. 26, 1967, Ser. No. 670,653 Int. Cl. G04c 3/ 04 U.S. Cl.58--28 1 Claim AISSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTIONField of the invention During the normal running of the regulator, theresistance and condenser introduce into the circuit a time constant of avalue such that the condenser charge maintains the blocking polarisationof the transistor at a value which is variable yet suicient to preventit from becoming conductive under the action of secondary electricalpulses of the same sign but dcphased with respect to the electricalmaintaining pulses, the latter pulses along can unblock the transistorwhen the condenser is charged or partially discharged, on the otherhand, when the time piece is energized, the charging current of thecondenser produces the starting pulse for the regulator. Before thecondenser is charged, the secondary pulses render the transistorconductiveand thereby assist momentarily in initial acceleration of theregulator.

Description of the prior art In the prior art circuits, nothing isprovided for cancelling each second pulse, wherefore all pulses are usedfor driving the mechanical oscillator, such being undesirable,chronometrically speaking.

SUMMARY OF THE INVENTION The invention is a self-starting circuit whichuses only one half of the pulses by removing each second pulse. During astarting period, all positive pulses are used for oscillator driving soas to allow a self-starting feature, but during the running frequencyperiod all the secondary pulses are eliminated.

In the prior art circuits, nothing is provided for cancelling eachsecond pulse. Thus, all pulses are used for driving the mechanicaloscillator. It is not desirable, from a chronometrical view point todrive an oscillator for instance a balance wheel twice at each completeoscillation so that it is useful as the present arrangement teaches, toeliminate each second pulse whereby only one pulse is applied to theoscillator at each oscillation thereof.

An elimination of each second pulse is desirable but at the same timethe device must be self-starting.

Condenser 17 of the invention is not directly connected to emitter 9 oftransistor T, but is connected to the emitter through the source ofcurrent.

In the circuit according of the invention, the base of transistor T issubstantially at the same tension as the collector. In this condition,the transistor is very conductive and a strong current circulates in theoutput circuit, giving a strong driving pulse to the balance wheel.Owing to the characteristics of the transistor, to the output current inthe circuit, corresponds an input current in the clrcuit which has forconsequence to load rapidly the condenser 17, as it would be the case ifa weak resistance was put in parallel with the resistance 18. Thus, theconstant of time is momentarily reduced to a value of 0.1 second, forinstance. Transistor T is thus rapidly in a condition where it can usethe initial deviation of the balance wheel and apply to it maintainingpulses.

The resistance and condenser are connected to the base of the transistorfor introduction into the circuit (during normal regulator running bythe resistance and condenser) of a time constant of a value for themaintaining by the charge of the condenser of a blocking polarization ofthe transistor at a value suicient to prevent it from becomingconductive under the action of secondary electrical pulses of the samesign but dephased with respect to the electrical maintaining pulsescapable of unblocking the transistor as the condenser is partiallydischarged.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of apart of a regulating device for the electric timepiece;

FIG. 2 is a cross-section on the line II-II of FIG. l;

FIGS. 3, 4 and 5 show in diagrammatic form various stages of therelative movement of a movable part of the regulating device withrespect to its xed part;

FIG. 6 shows a diagram of pulses, as a function of time;

FIG. 7 is a diagram of an electrical maintaining cir cuit for theregulating device shown in FIGS. 1 and 2; and

FIG. 8 is a diagram of the Variations in voltage as -a function of timebetween two points of the circuit shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT The regulating device, orbalance, features opposed magnets 1, 1 and 2, 2', secured in pairs onplates 4 mounted rotatively on the frame of the clockwork by means ofstaff 5.

The balance is subject to the action of a spiral return spring (notshown).

Two coaxial coils 6 and 7, xed with respect to the balance and havingtheir axes parallel to the axis of stal 5, are disposed so that theirturns can intersect the parallel groups of the lines of force of magnets1, 1 and 2, 2. These groups are movable around the axis of staff 5,according to the amplitude and the period of the balance.

Pole pieces 3 and 3 each join the two poles of opposite polarity ofmagnets 1 and 2, on the one hand, and of magnets 1' and 2' on the otherhand, so that the balance carries a magnetic iield including two gaps1-1 and 2-2 which sweep respectively and in succession over the turns ofcoils 6 and 7.

It is to be noted that, instead of coils 6 and 7 being superposed, asshown, they could be arranged one inside the other or could beoverlapped one within the other by simultaneous winding.

k As the balance passes through its position of equilibrium, magnets 1,1 and 2, 2 are disposed symmetrically with respect to coils 6 and 7 asin FIG. 2. Pairs of magnets 1, 1' and 2, 2' are fixed in the vicinity ofthe rims of plates 4 so as to sweep over the turns of the coils atmaximum linear speed.

The variations in flux, and the induced voltages which result therefromwithin coils 6 and 7, can be split up into three essential stagescorresponding to the dilierent rela- 3 tive positions of the magneticfield of magnets 1, 1 and 2, 2 with respect to coils 6 and 7 (FIGURES 3,4 and 5) In FIG. 3, group 2-2' of the field is shown as beginning tosweep over a part of'the coils so as to coincide, as shown in FIG. 4,with the position of equilibrium of the balance, the turns of coils 6and 7 intersecting the maximum lines of force of the magnetic field.

In FIG. 5, the field is shown as tending to move away from the coils,only group 1-1' still acting on a part of the latter.

These diHerent stages of movement give rise, in the circuit of coils 6and 7, to the voltage pulses indicated in FIG. 6.

Successive trains of three pulses appear at each halfperiod. A mainpulse C or C' is framed by two secondary pulses B, A or A', B' with asign always opposite to that of the main pulses of the same train. Thesecondary pulses of type A, A' correspond to the stage of FIG. 3, whilethe secondary pulses of type B, B' correspond to the stage of FIG. 5.

The main pulses of type C, C', which are positive or negative accordingto the direction of the half-oscillation of the balance and of anamplitude greater than that of the secondary pulses, correspond topassage to the position of equilibrium (FIG. 4), simultaneously by theturns of coils 6 and 7.

During the process of maintaining the movement of the regulator byelectromagnetic pulses, only the positive pulses, due to the fact thatthe circuit of FIG. 7 is transistorized, are adapted to unblocktransistor T and render it conductive. The negative pulses (inchain-dotted lines in FIG. 6) do not give rise to any maintainingenergy.

From among the positive pulses shown in FIG. 6, we select only thosenecessary (i.e., the main ones), for the maintenance of the regulatormovement.

The electrical circuit (FIG. 7) comprises a battery of which negativepole 8 is connected to emitter 9 of a transistor T of the n-p-n type.Collector 10 is connected to end 11 of coil 6. The other end 12 of coil6 is connected to positive pole 13 of the battery.

Base 14 of transistor T also terminates at 13 through the medium of coil7, having ends 15 and 16 in series with condenser 17 having a capacityC.

The circuit also includes a resistance 18 with an ohmic value R andconnected between positive terminal 13 and end 15 of coil 7 so as to bein parallel with the assembly consisting of coil 7 and condenser 17.

A second condenser 19, with a capacity C', is interposed betweencollector 10 and base 14 of transistor T, which condenser 19 serves tosuppress oscillation in the circuit which would occur at its ownfrequency, by reason of the fact that since coils 6 and 7 are arrangedone against the other, they have a certain coefficient of mutualinduction. Condenser 19 dephases the voltages of the coils at this highfrequency sufficiently, but has no effect on the very low frequencypulses, which are alone used.

When the FIG. 7 circuit is under no Voltage, the balance is stopped inthe position of equilibrium, as shown in FIGS. 1 and 2, magnets 1, 1'and 2, Z' being disposed symmetrically with respect to coils 6 and 7.

At the moment of connecting the circuit to the source, condenser 17being discharged (the voltage at its terminal is equal to zero),interconnected points 14, 15 and 16 are subjected instantaneously to thepotential of positive pole 13.

This polarization voltage has the effect of rendering the transistorconductive. A current is set up from positive pole 13, through coil 6and towards collector 10` and emitter 9, to terminate at negative pole 8of the battery that produces a starting punch applied to the oscillator.At the same time, the current in the circuit of base 14 chargescondenser 17 through coil 7. This has the effect of reducing thepositive polarization of base 14 and of causing the collector current tofall very rapidly. The vcollector current establishes itself at a fverylow value,

4 when the charge of condenser 17 brings the potential of base 14 to avalue close to the conduction threshold of transistor T.

The initial pulse, on the placing of the circuit under voltage, has theeffect, in passing through both coils 6 and 7, of inducing a magneticfield which, coupled with the field of magnets 1, 1' and 2, 2', producesan important force displacing the balance. (It is to be pointed out thatthe main effect is due to coil 6, rather than the coil 7.)

In turn, the displacement of the balance, and the associated magneticfield, induces in coil 7 a voltage of low value sufficient to initiatemomentarily conduction of the transistor, which is therefore polarizedin the vicinity of its conduction threshold. This induced voltage istherefore amplified and supplies pulses A', B' and C to coil 6.

This cycle causes self-starting and acceleration of the balance until ithas reached its normal running amplitude.

Moreover, and this is one of the essential aims of the invention, thecircuit described has the effect of also rendering inoperative, duringthe normal operation of the regulating device, the secondary positivepulses of type A', B' (FIG. 6) which are induced at each halfperiodfollowing or preceding the main positive maintaining pulse. This specialproperty of the circuit of FIG. 7 can be explained as follows:

Under normal working conditions, at each pulse crossing collector 10,the base current of the transistor charges condenser 17 to a voltagewhich, measured at its terminals, is close to the supply voltage of thecircuit. Condenser 17 is discharged, between the two successive pulses,through resistance 18 and in accordance with the exponential law whichdetermines the time constant T=CR. The values of R and C are chosen insuch manner that the time constant r is large with respect to the periodof the pulses to be amplified. The result is that the residual voltageat the terminals of condenser 17 is sufficient in comparison with thevoltage of the secondary pulses A', B for the polarization voltage notto permit the unblocking of the transistor.

The conduction threshold of the transistor not being reached, for pulsesof low amplitude, as is the case with the secondary pulses A' and B',the latter (in broken lines in FIG. 6) are not amplified.

After a time of about a half-period following the appearance of pulseB', which pulse has had no effect on the amplifying power of transistorT, pulse C arrives (pulse C being indicated in solid lines in FIG. 6).The latter pulse renders the transistor conductive owing to the factsthat it is higher than pulses A' and B and that condenser 17 hascontinued to discharge itself during this half-period, so that, at theinstant in question, its residual charge no longer has an inhibitingaction on the voltage of main pulse C (FIG. 6), which voltage aloneinitiates the conduction of transistor T, thus giving rise tomaintaining pulse through coil 6, at the same time as condenser 17 ischarged afresh.

In other words, the presence of condenser 17 and its special timeconstant prevent any secondary pulse, dephased with respect to the mainpulses, from priming the transistor, so that these secondary pulses,even were they of the same sign as the main pulse, are renderedinoperative.

This is evident from FIG. 8, which indicates, as a function of time, theform of the variable voltage U existing between emitter 9 and base 14 oftransistor T. The zero of the ordinates corresponds to that of theemitter potential. The successive voltage peaks a', c', b', d, c, a areproduced at the same time as the pulses A, C', B', B, C, A shown in FIG.6. The chain-dotted positive ordinate horizontal shows the conductionthreshold of the transistor T, which threshold is reached only by thevoltage Uc (peak c in FIG. 8) corresponding to the main pulse C (FIG.6). Moreover, the voltages resulting from the charging and dischargingof condenser 17 are clearly apparent between the successive oscillationtrains of the voltages.

The capacity of condenser 17 is essentially a function of theamplification coeicient of transistor T, but for the -balances generallyused and with the transistor employed, the capacity of condenser 17 ispreferably bctween 0.4 nf. (,B large) and 1.5 uf. small). Resistance 18may have an ohmic value ranging between 2.5 and 4 mohms, so that it ispossible to accept for the time constant -r which has been mentioned,values corresponding to 1 to 6 seconds (1 sec. STSG sec.). Moreover, ift is the period of the oscillator, experience shows that 1- minimum mustbe at least equal to 3.5i for the polarization not to vary too rapidlyfrom one pulse to the next following.

Eliminating any maintaining pulse which is dephased with respect to thepassage of the balance to its position of equilibrium is favorable toattaining maximum efciency of the whole device. The maintaining pulsesare produced at the moment when the magnetic field intersecting theturns of the coils is at the maximum (FIG. 4). Since the transistorremains blocked during the secondary pulses and between the variouspulses, the supply current is reduced to the leakage current of thetransistor, which is very low by itself.

This features is favorable to the isochronism of the movement andenables the latter to be regulated by displacement of the pulse relativeto the position of equilibrium of the balance and by means of only onedriving pulse per complete oscillation of the oscillator.

Although the secondary pulses are inoperative during the normal workingconditions of the regulator, the position is not the same at the momentof starting when, since condenser 17 is not yet fully charged, the firstpositive secondary pulses A', B can momentarily render transistor Tconductive and consequently assist, for a brief moment, is setting thebalance going by a supplementary, but temporary, supply of energy.

With the timepiece being energized, the charging current of thecondenser produces a starting pulse for the regulator. Then, preliminaryto the charge of the condenser, secondary pulses render the transistorconductive for momentarily assisting in the initial acceleration of theregulator.

The combination allows the following operations: (1) Strong selfstarting of the oscillator due to the fact that the current, at themoment of energizing the circuit, passes freely through the condenser 17which is unloaded so that both coils 6 and 7 receive current and bothact on the oscillator for imparting to it a strong impulse like a bigpunch;

(2) Very rapid 'acceleration of the oscillator up to the runningamplitude due to the fact that, during this starting period, all thepositive pulses (main pulses as well as secondary pulses) are used. (Thecondenser 17 is not suiciently loaded for having an inhibiting action);and

(3) Very favorable running condition from the point of view of theisochronism since, once the running conditions are reached, thesecondary pulses are no longer used (the condenser 17 being loaded), sothat only the main pulses are used, i.e., only one pulse for eachcomplete oscillation of the oscillator is applied thereto.

5 I claim:

1. In a self-starting oscillating regulator of an electric timepiececomprising:

a shaft having two rim plates rotatably mounted thereon andelectromagnetic means for maintaining the oscillations of the regulatorand including:

(A) a pair of magnets carried by each of said plates and each pair ofmagnets being4 positioned directly opposite the other pair of magnets,and

(B) an electronic self-starting circuit with each second pulse removedand constituted by:

(1) a current source,

(2) a transistor,

(3) a resistance connected to the transistor ybase through the currentsource,

(4) a condenser connected to the transistor base through the currentsource with the resistance and condenser being mounted in parallel, and

(5) a pair of stationary coils generating regulator-driving pulses uponmovements relative to the magnets with a relative movement between themagnets and coils occurring during oscillations of the regulator andwith normal regulator operation being characterized by a time constanthaving a value for maintainance by the condenser charge of a blockingpolarization of the transistor at a variable value for preventingconduction by the transistor under the action of secondary electricalpulses of the same sign but dephased with respect to the maintainingpulses, the maintaining pulses being such as to unblock the transistoras the condenser is charged or partially discharged and the secondarypulses rendering the transistor conductive for momentarily assistinginitial regulator acceleration.

References Cited UNITED STATES PATENTS 3,046,460 7/1962 Zemla 58-233,351,833 11/1967 Gerum 58-23 FOREIGN PATENTS 4/ 1965 France.

U.S. Cl. X.R. 58-109; 318-129

